1. Field of the Invention
The present invention relates to a steady rest for central clamping of rod-shaped workpieces with a circular diameter on a lathe with three holding elements arranged in the same plane and provided with rollers, of which the two outer holding elements can be swivelled about an articulated pin mounted in a housing and the middle holding element can be adjusted in a straight line in relation to the workpiece, with the ability to supply coolant or lubricant to the workpiece by means of ducts worked into the housing and the holding elements.
2. Description of the Prior Art
In steady rests of this kind, the coolant or lubricant flows to the middle holding element directly through a duct worked into the housing or a housing cover and this duct opens into a slot-shaped recess also provided in the housing. In this case, a further duct worked into the adjustable middle holding element is connected to the recess, which is sealed all the way around by means of a seal inserted in the housing or the housing cover.
Although this supply of coolant and/or lubricant to the roller of the middle holding element or the workpiece has proven effective, the adjustment movements of the middle holding element can cause the seal around the recess to become damaged after a relatively short time, with the effect that coolant or lubricant can emerge from the recess and get into the inside of the steady rest housing. Not only does this impair the lubrication of the adjustable components and their function, it can also lead to rust on the control cams and other locations, meaning that the required high level of clamping accuracy of the steady rest is no longer provided.